1. Field of the Invention
The present invention relates to a micromachine which includes a structure body and an electric circuit having a semiconductor element over one substrate, and a method for manufacturing the micromachine.
2. Description of the Related Art
A micromachine is also called MEMS (Micro Electro Mechanical Systems) and MST (Micro System Technology) and refers to a comprehensive system combining a micromechanical structure body and an electric circuit. The above structure body is different from a general semiconductor element in having a three-dimensional structure, a part of which is movable in many cases. The structure body can have various functions like a passive element such as a sensor, an actuator, an inductor, or a variable capacitor, a switch, or the like. The electric circuit is generally formed using a semiconductor element and can control the operation of the structure body, or receive and process a weak signal outputted from the structure body.
Further, micromachines can be classified into two groups according to their manufacturing methods. One is bulk micromachines in which structure bodies are manufactured using crystal anisotropy of a silicon substrate, and the other is surface micromachines in which three-dimensional structure bodies are manufactured over various substrates by stacking thin films (see Reference 1: Japanese Patent Publication No. 3590283). In particular, surface micromachines have been actively researched, especially in the United States, because a structure body and an electric circuit can be formed over one substrate.